Hell Unleashed: The Making of Wrath of the Titans

Trevor Hogg chats with Visual Effects Supervisors Nick Davis, Gary Brozenich, Olivier Dumont and Bryan Hirota as well as CG Supervisor Martin Chamney about their work on Wrath of the Titans…

“It certainly changed the stylistic approach towards them,” states Visual Effects Supervisor Nick Davis (The Dark Knight) who collaborated with filmmaker Louis Leterrier on Clash of the Titans (2010), while Jonathan Liebesman helmed its sequel Wrath of the Titans (2012). “With the first movie we had more of a comic book fantastical moviemaking style and when we came to the second movie, it was a rougher, rugged documentary realistic style of filmmaking that Jonathan wanted to do.” Replacing the Kraken as the signature creature in the cinematic franchise is the volatile Greek mythological deity who fathered Hades, Hera, Poseidon, and Zeus. “Probably the most challenging part was Kronos and the end battle. How do you design a 2000 foot tall creature that gives you scale, is able to interact with objects, an army, and people, and yet come up with a sequence that works? When you start having something that big fighting people that small it’s very hard to give them anything to do.” Several different artists were approached early in the design process. “We can up with this whole lava pyroclastic flow and look for him. He is a creature that is constantly emitting volcanic mushroom clouds out of his back, body, and neck, which gives him a massive scale, size, and mass. Every time Kronos moved there would be lava flowing off of him. We looked at different types of software that could simulate these enormous pyroclastic clouds. Kronos became technically a huge challenge in the amount of rendering and computer space he took up.”

“It was an ever evolving process,” explains Nick Davis as to the creative relationship between him and the man behind the camera. “Jonathan and I would sit down; we talked about sequences and played around with storyboards and pre-viz. He liked to be highly fluid and free on the set. Take something like the Tartarus Sequence, we pre-viz it, planned it and had some shots that we wanted to get but there was a certain amount of freedom that we let him have so on the set he and Sam [Worthington] could to a certain extent change things on the go. We had to think on our feet and be quite quick to adapt. That’s Jonathan’s style; he likes not to be completely constrained as a filmmaker by too much planning, and absolutely rigid pre-viz and shot design.” The ancient period was recreated with the help of CGI. “As far as the visual research for the designs we did a lot of work online and hired a lot of great artists to come up with looks and feels for the creatures and environments. We tried to base things off a real canvas of the real world but when it came to a lot of creatures we had to make something unique.” The number of VFX shots did not increase. “We ended up with about 900 which are about the same as the last movie; some of them were a lot harder. We did a lot more creature work in this one because we had the Makhai, Kronos, Cyclops, and Chimera.”

We always go out to tender and then look at what teams are available and the skillsets that they have,” explains Nick Davis as to how he chose the various VFX facilities to work on the fantasy epic. “We went with MPC because they had a great ability to deal with complex fluids and water simulations which led to them doing the pyroclastic clouds and all the lava simulations; that gave them entire Kronos sequence which naturally made them our biggest vendor. I went with Framestore to do the Cyclops because their skin shader rendering is the best that’s out there; we wanted to make him completely photo-realistic in all of his skin, hair and finishes.” The UK based VFX facility was also responsible for the Labyrinth Sequence “because their environment work was extremely good as well. I went with Method in Los Angeles to do a big section of interior environment work. The same thing they had a very good team available. They gave us a very aggressive bid to do a huge section of Tartarus and did a fantastic job.” Nvizible was recruited to help out with creating the CG environments for the Tartarus Sequence while some last minute alterations had to be made. “Pixomondo helped out when we ran into trouble at the end. We needed some additional firepower and they stepped in and did a whole bunch of 2D and 3D comps for us.” The VFX process was tailored to maintain a visual uniformity. “We tried to make sure that you don’t have too much crossover in the work; they were doing their individual sequences. I made sure they were true to the designs and whenever we had any effects that overlapped, they were always talking and matching. In this day and age facilities do tend to share assets, technology, and are much better in having an open dialogue with each other.”

“We got on-board early with Nick in pre-production,” states Moving Picture Company VFX Supervisor Gary Brozenich who oversaw the development of the signature creature for Wrath of the Titans. “Kronos had to have a human type of look and had to be made out of lava and pyroclastic. Nick had a good idea of the bigger parameters about what he wanted the creature to look like and gave us a lot of room to play with that.” The task was a massive undertaking. “We had quite a substantial effects team on the show. We had over 30 effects artist, which may have been closer to 40 at one point when we were at the peak.” Previous assignments in producing fluid simulations from Poseidon (2006) onwards were indispensable along with exclusive outside vendor rights to the software program Flowline developed by Scanline. “It gave me the confidence to be able to talk to Nick and to do designs on Kronos with the idea I knew the team here were savvy enough and had the tools in place to be able to do it.” As much as reality was a goal a large part was also based on fantasy. “Realistic looking lava in a daylight environment coming off a 1200 foot creature is not something anyone is going to hold up a direct reference against it. There was a huge amount of creative interpretation that had to go into it.” Brozenich adds, “He was a hell of a creature.”

Mother Nature turned out to be an ally when simulating the flow of lava. “There were so many live volcanoes that were erupting at the time we started discussing the project and Kronos,” recalls Gary Brozenich. “Camera teams were going out filming it from helicopters and close-up with amazing lenses in HD cameras; there was a wealth of information out there. We’d look at it and know exactly how lava performs and pyroclastic clouds move, and what scale they are, and how slow or fast they should be. Once we understood what those rules were we could talk to Nick and Jonathan, the director, about how they wanted to bend that.” There was a major advantage in not having to deal with simulating water. “Lava is something that could be slightly more forgiving because it’s not something we see day to day.” The task was more difficult by depicting the sweltering liquid in daylight. “We’re used to seeing dark environments with bright lava but typically when you expose lava on film it will go almost flat.” Other natural elements associated with lava had to be taken into consideration. “I would say it was at least six months to get to a point where we had something that stood up and represented what we all see as a pyroclastic cloud in our head. There was one particular image which Jonathan and Nick both fell in love with which was something from Chile. There was a lot of electricity within the source of the volcano as it was coming up. It was filmed at a darker hour so you could actually see quite a lot of colour, black and lightning in the pyroclastic. One of the biggest challenges for us was to try to translate that into a stark day lit environment and get that same scary, foreboding feeling.” Brozenich proudly admits, “It’s the best and hardest effects work we’ve ever done.”

“Jonathan likes your to feel like you’re in the trenches with the soldiers,” believes Gary Brozenich, “Everything is gritty. If there is stuff being kicked up in their face it’s being kicked up in your face too.” The documentary approach influenced the design process. “The creatures had to have the same earthy organic ripped out of the ground and stuck in front of the camera feel.” MPC was responsible for handling the Chimera Sequence which features a rhinoceros-size two-headed creature that breathes fire. “It was like a flamethrower with a bit of Napalm mixed in with it. We had good references for that and onset would always have flamethrowers there. We needed them a lot for interactive light and flames during the filming. The bigger challenge for the Chimera was how we were going to get it to go from a liquid state from one head to a fire state from the other. It spews a fueled petro which is heated by lion head creating the flame that the Chimera throws. We also did a massive elements shoot with a bunch of flamethrowers with all the special effects guys.”

“We did the opening Dream Sequence where Perseus has a premonition about Kronos and wakes up in a cold sweat,” remarks Gary Brozenich who also had to turn the Gods to stone. “It always had to happen in close-up moments. We weren’t exactly sure how to make that work and had to let the actors deliver their lines. We had to make sure that all the drama was there. It was a lot of clean passes and stuff shot onset. We left it down to the actors to become rigid at the point they felt they should; we had to work around their faces as they still had to continue to move their mouths, noses, and eyes to get the performance across. The biggest trick was trying to work with the plates and the drama performance but still make it clear that something was happening and they were turning into rigid material.”

“We did the Makhai which are these two-torso creatures born from Kronos and are meant to be welded together from the dead souls of warriors,” states Gary Brozenich who was pleased with the end result which is on full display with the End Battle Sequence. “They have bits of armor sticking out of them, plates coming out of their head with rough hewn swords, and spears that have been picked up along the way.” The creature was created to meet the dramatic needs of Jonathan Liebesman and Nick Davis. “The Makhai had to be these ultimate fighting creatures that have no other purpose to be on earth other than to kill. They had to put something on the ground for the humans to interact with and to have a hand to hand fight to keep the action going and the excitement in the film. Kronos flings lava towards the humans and within that lava are little fireball meteors that carry these creatures down to the battlefield; they go in and give Rosamund Pike [Made in Dagenham] and all the soldiers something to fight with.” Comparing the battle scene with those found in the The Lord of the Rings trilogy, Brozenich notes, “The Orcs were brilliant creatures and set a visual standard for what we all could get away with in making something that fits within a rating and be truly horrifying. There is a visual style to that film which is large sweeping camera moves. It’s got an epic scale that is contrary to the way Jonathan wanted to make this film; he was more of a Black Hawk Down [2001] or Private Ryan [1998] D-Day Beach Scene kind of guy.”

Practical effects were incorporated into the End Battle Sequence. “It went very well because we got in with the stunts and the special effects guys very early on in pre-production,” says Gary Brozenich. “Nick was aware of the fact that we were going to have to deal with having not only stunt guys, as many as 10 or 12 of them fighting one Makhai but also having some of the principle actors going face to face with them as well. We needed to come up with solutions with the stunt guys on how we could not impose too much on the set. We would have trouble either cleaning them out or they would get in the way of us doing the shot that we wanted. However, they would be well enough rehearsed to know how big the creature was and how it would behave.” Fights were choreographed by the stunt crew and videotaped. “We would animate on top of the test footage so it was a bunch of guys in sweat suits on an empty stage and they had a stand in Makhai in the middle of it; we even explored ideas of strapping two stunt guys together to fight them to represent the two torsos.” Once the “coolest piece of action” was chosen a stuntman would be placed on stilts with arm extenders. “They would set the camera up to the fight that was rehearsed, pull the Makhai performer most of the time, and run the scene again; that was always combined with special effects because there was stuff blowing up everywhere. There were constantly things on fire, explosions happening all around them, and everything that was coming off of Kronos. It was something that was heavily planned from the outset and if we had not done that we would have had a very different looking sequence in the end.” An ability to adapt to the needs of the director was essential. “We had rehearsed scenarios to the point where we could plug those ideas into all the different setups. One thing that was hugely beneficial as well was that Nick was the second unit director on the film as well as the visual effects supervisor.”

“About 25 or 30 of our biggest shots were delivered by us as stereo,” reveals Gary Brozenich who had to accommodate the post-conversion 3D process. “Mainly, [it had to do with] the full CG ones because that’s the standard procedure in which the shows go through. Aside from that we had quite an extensive list of material we had to deliver to the external vendors that did all of the dimensionalization. Probably the biggest challenge was making sure that there were enough stereo moments integrated into the sequences. Part of that was the filming process and part of that was with our CG to make sure that we were giving enough stereo interest at the right moments without overwhelming the audience or not giving them enough of it.”

With sets needing to be built the look of the Underworld was already established by the Art Department and director Jonathan Liebesman. “They had a lot of concepts,” explains Method Studios Visual Effects Supervisor Olivier Dumont when describing the task which required the combined effort of facilities in Los Angeles and London. “Method London was involved in the pre-production to work on the concepts for Tartarus which is a big tower where Kronos is embedded in rocks.” The worlds outside and inside the tower had to be constructed. “Tartarus is a double pyramid; it’s floating in the middle of the Underworld which is a huge inside out sphere where you have mountains on the ceiling and clouds. Basically, it’s a big cave in the centre of the earth. In the middle of this cave you have this double tower.” To create the floating effect, Dumont states, “We played a lot with the atmosphere by adding more and more clouds in front of the tower so you feel that it’s faraway.” With the look of the Underworld already established, visual research was not a major concern. “It was a matter of getting the right scale and environment with the clouds and the stair that is connected to the tower. We didn’t have to do too much research; it was more about finding a way to show it that would please the director.”

“The main part that we worked on was inside the tower,” reveals Olivier Dumont. “In there we had to deal with Kronos. We received a model of Kronos from MPC that was a low resolution because of incompatibility with our pipelines; it wasn’t a problem because we knew that the stage that Kronos during our sequences wasn’t the same as when he is outside so we had some liberty with our own design. We had shots that were drastically different from what MPC had to do on their shots. We had a lot of close-ups, for instance, on Kronos’ head and other angles that they weren’t using in the outside.” A major change on the part of director Jonathan Liebesman resulted in some major alterations. “At the beginning, Kronos was supposed to stay in the two mountains on each side of him where he is embedded. Jonathan felt that it didn’t have enough tension during the escape sequence where Perseus is freeing Zeus who is attached inside the chamber; he wanted to feel that they had to run out because Kronos is getting free.”

“I’ve never seen a mountain collapsing before so I’ve no clue on how it should look like,” states Olivier Dumont. “We saw footage from explosions in quarries but nothing was looking like a big scale. After a lot of research we came to an agreement with Nick that the closest would be a glacier breaking apart. You have this big piece starting to fall and then quickly it collapses on itself and into smaller parts which are breaking again on itself, until it becomes like a fluid in the end. We had to reproduce that for this sequence so there were a lot of setups. The way we did it was to build a tool that would fragment the mountain automatically. We had the texture artist draw a map that would represent the big pieces on the mountains which would then be fragmented. Our tool built a volume inside the mountain based on the map; we used these little hand animated pieces to drive a simulation with another tool that would break those pieces into smaller ones and then into particles to simulate this glacier falling. Obviously, on top of that you need to add a lot of dust and smoke.” HD glacier footage found on YouTube and BBC documentaries were indispensable visual references for the team at Method Studios. “The modeling was also a big challenge because we had so many different camera angles in Tartarus; the way to handle that was to build blocks basically like Lego to the construct the tower. We had by the end over 7000 pieces to build the full Tartarus.”

“Hades captures Zeus and attaches him in the Kronos chamber so to drain his powers and give them to Kronos so to wake him up,” says Olivier Dumont. “The draining effect is something Jonathan wanted to show. This lava fluid that is coming out of his veins and Zeus is attached with chains on two spikes. The magical chains are acting as a drainer.” The lava becomes larger as it flows toward Kronos. “The lava was a big effect because we needed to represent that in a realistic manner but we had so many different sizes to show.” The hot liquid had certain characteristics that needed to be imitated to make the CG version appear realistic. “Lava can be fluid or like a rock; you have parts that are cooled down so they’re moving slower than the parts that are very hot. You need to make sure that it’s believable in every scale. On Zeus’ arms it was very small, like tendrils, when you are on the ground it’s a little bit bigger and then on the bridge it’s way bigger. We had to watch a lot of references, for instance, from Hawaii on how the lava reacts in different scales. The main challenge was to build the lava and to have the ability to art direct it. Even if you feel the lava is going too fast or too slow you need to be able to change that without having to go through the whole process; that’s why we used the strategy of adding something that is driven by simulation but is sculpted by hand to get the best detail.”

“We did over a 160 shots and we had to do a full stereo for 21 shots,” states Olivier Dumont. “It’s a lot of work but it doesn’t change the process that much because you go from one image and you make two. When you’re dealing with full stereo you need to make sure for instance that the left eye and the right eye are rendered the same way. If you have just a little difference between the two it jumps at you right away. It’s very hard usually to fix it. You don’t have room for mistakes. If you were rendering as one image you do a little paint and then it goes away. But if you have to do it for both eyes then it becomes trickier.” The process is becoming easier. “We have more tools nowadays to deal with that kind of thing. Nuke is pretty good in generating a second eye from one eye.”

“Nvizible was responsible for creating the VFX environments for the backgrounds in the shots entering the underground dungeon of Tartarus, and within the main chamber where Kronos is encased in the rocky walls,” states CG Supervisor Martin Chamney who works for the London, England based VFX company. “Many of the plates came to us with large portions of green screen that we replaced using a couple of master digital matte paintings. We had an automated system that took plate data in to Nuke, and essentially orientated a nodal camera inside the DMP environment. This widget configured the correct line sight, field of view, and depth of field. The creative challenges revolved around gauging the correct motion and quantity of atmospheric enhancements throughout the changing events of the storyline. The digital matte paintings were supplemented with fx elements – flaring fire, incandescent sparks, smoke, heat haze and fogging. The amount of fx was gradually increased in the shots leading up to the epic moment where Kronos breaks free. Much of the skill was in integrating these elements in at the correct depth in every shot.” In regards to the visual research, Chamney remarks, “A vfx treatment of glowing incandescent molten metal, dripping metal and sparks, was devised for a number of augmented weapon shots. We researched the look and colouration of molten metals, when hot and cooling down, as well as sparks created from the kind of work that blacksmiths carry out. During the look development process for the Armillary Sphere, a number of design concepts for the inner parts of the mechanism were produced. This included the spoke arms that Tartarus is held in place with. The inspiration for the surface and the thick cross-section of the model was taken from a geode, and the inner maze detailing was fashioned on corroded hand carved metal etchings from reference photos.”

“Our biggest challenge on Wrath was creating the long fully native stereo CG shot which takes place in Hephaestus’ forge,” says Martin Chamney. “A huge Armillary Sphere, containing a mechanized structure of the earth which has been set in to motion by Hephaestus, breaks open like segments of an orange. The live-action camera move which arcs around the sphere is then extended with a CG camera move that translates into the center of the sphere containing a pyramidal model of Tartarus, symbolizing the journey through the Underworld. The original 6ft diameter prop of the sphere, made of huge curved continental plates, was lidar scanned and rebuilt as a CG model. Laying out over 200 continental parts, for texturing and then deforming back to the correct position was a detailed process. The inner part of the sphere didn’t exist as prop, so we relied solely on early art-department drawings and the previs model. Nick Davis gave us direction for the design of the miniature maze [which represents the real size Labyrinth in the story] the supporting spokes, and the miniature of Tartarus. The CG had to look completely real and tactile, and completely match the real world prop. Texturing was one of the biggest challenges, having sufficient resolution for a camera that is constantly moving closer to its subject. We ended up devising an indexed set of 20 uv texture tiles, to give us ample coverage on all areas of the model. Managing all this was achieved using Mari. Also utilizing ptex vector displacements exported from Mudbox gave us a lot of control over high frequency surface detail. Rendering such a long complex stereo shot was quite a challenge, with all the enormous amount of point cloud data for shadow occlusions and colour bleeding, and the many CG passes required to make up the highly detailed image. The original previs by Nvizage was approximately 20 seconds, but then came a decision to continue the camera move further inside Tartarus which extending the timing of the shot to nearly a minute. Additional geometry was constructed of a rocky bridge, surrounding walls, and the entrapped Kronos, all detailed to look like a miniature that had been handcrafted.”

“Stereography certainly made everything more complicated,” admits Martin Chamney. “For our hero CG shot, there is a lot to consider when deciding where the audience should look. The shot starts out wide in the practical set of the forge, but the camera ends up translating into an incredibly small space. To make the shot work, we had to reconstruct the whole set and dimensionalize the live-action background plate and actors. Throughout the whole shot we had complete control over the stereo depth of the image. With a combination of work in Nuke and Maya we animated the interaxial and the convergence of the stereo camera at various waypoints. We were able to direct which area of the image would be on the screen plane, as well as how much geometry would break in to negative screen space. A macro level of detail is explored throughout the shot, and we experimented with a varying f-stop to control the depth of field. The effect of a shallow depth of can ruin the enjoyment of stereo parallax, and the shot was very subtly crafted to retain both great stereography and the experience of being right inside a miniature model.”

“Shortly before Christmas I received an email from Greg McMurray who was hired by Nick to help oversee the Santa Monica office of Method,” recalls Pixomondo VFX Supervisor Bryan Hirota. “With so much work to do and Nick primarily in London it’s often helpful to have someone you trust on the ground. Greg asked me if I was interested in helping him out by picking up around 20 shots that needed to match in with the shots that were being done at Method. At this point Method had some hero shots to offer up as reference. We took the scans and spend a week mocking up the shots to look roughly like the hero shots. Luckily for us Nick happened to be in Los Angeles and we were able to spend some time with him before he went back to London and he could articulate to us in person what worked/what didn’t work about our shots. We would then communicate with him by sending him quicktimes and cinesync’ing with him. As some of the effects in the shots [like the god weapons] were evolving – once a look was achieved at Method – Greg would bring by shots and then walk me through visually the key points. Over the course of the show Nick was in town a couple times and we met with him those times but the communication was primarily cinesyncs and email.”

“We didn’t need to do much research as we were following Method’s lead,” states Bryan Hirota. “The only stand alone shots were a couple where we had to dirty up Zeus’ outfit and for that shot the director made a Photoshop himself that was a pretty good guide for what he wanted. That innocuous looking shot was actually pretty complicated as the cloth/folds/etc. of his robes needed to be tracked perfectly to put scorch marks all over them.” Hirota observes, “Working in a short time frame is always challenging. On one hand the blueprint was laid out for us nicely by Method. They had their hero shots that were approved, and provided us ultra high resolution spherical bubbles that contained the Underworld environment. Nick provided us a layout frame that showed the basic section of the bubble we were to look at and method provided us with the library of smoke/embers/fire/smoke to fill out the Underworld. So we had all of the pieces needed… the challenge for us was making sure we were able to get up to speed and produce shots that would fit seamlessly in with the other shots. There’s always a ramp up time to fine tuning to the particular sensitivities of any project.”

“The conversion on the last movie was a last minute decision,” states Academy Award-nominated Visual Effects Supervisor Nick Davis when addressing the highly criticized 3D post-conversion of Clash of the Titans. “This time around it was a decision made from the get go. A lot of shots and sequences were designed with stereo in mind. There was a lot more time to actually do the conversion. The conversion was planned and a huge team was involved. Six months was spent doing the conversion as suppose to six weeks. We edited and shot the movie with many shots planned out and thought out in advanced. In that respect we were well ahead of the problems of the last time.” IMAX was not an issue during the principle photography. “We didn’t shoot native IMAX; it’s going through their conversion process and being scaled up like most movies that they put out.” Reflecting on Wrath of the Titans, Davis states, “The Makhai was always a slightly favourite creature for me; they came out very well at the end in their design and the way they moved. I do love the Cyclops. People in the know will be quite impressed with the photo-realistic of the skin, the hair and the whole dynamic of them. It’s impressive work.”